\chapter{Conclusion}
\label{chap:conclusion}

TO BE DONE\ldots

% As WS-*  and similar approaches, our work enables the specification and
% programing of  crosscutting aspects (i.e., atomicity, security, exception
% handling, persistence). In contrast to these approaches, our work specifies
% policies for a services' composition in an orthogonal way. Besides, these
% approaches suppose that non-functional requirements are implemented according a
% the knowledge that a programmer has of a specific application requirements but
% they are not derived in a methodological way, leading to ad-hoc solutions that
% can be difficult to reuse. In our approach, once defined {\em A-Policies} for a
% given application they can be reused and/or specialized for another one with the
% same requirements or that uses services that impose the same constraints.           
% 
% Furthermore, unlike methodologies and approaches providing best practices
% presented above, the main contribution of our proposal is that, integrated to a
% method that proposes meta-models at different levels (CIM, PIM and PSM) and
% extending the PSM meta-models, it enables  the design and development of
% services' based applications that can be reused and that are reliable.   